MAJOR — Use With Caution
🔴 CAUTION — Major interaction between St. Johns Wort and Simvastatin. Avoid unless under direct medical supervision.
Evidence level: MODERATE
St. John's Wort makes Zocor much less effective at lowering cholesterol.
CYP3A4 induction reduces simvastatin bioavailability significantly.
St. Johns Wort affects how your body processes Simvastatin, which may change its effectiveness. Your doctor may need to adjust dosages or consider an alternative. Do not change doses on your own.
Take Simvastatin in the evening when hepatic cholesterol synthesis peaks (exception: atorvastatin and rosuvastatin have long half-lives and can be taken any time). St. Johns Wort can be taken at a separate meal. Avoid St. John's Wort (reduces statin levels via CYP3A4 induction) and grapefruit extract (increases levels). Report any unexplained muscle pain or weakness.
Higher risk with: liver impairment, genetic CYP enzyme variations (poor or ultra-rapid metabolizers), older age, polypharmacy (many medications).
Monitor for any unusual symptoms and report them to your healthcare provider promptly.
Ask your doctor: "Is there a safer alternative to St. Johns Wort that I can take with Simvastatin?" Bring a list of ALL supplements and medications you take.
Statin interactions often involve liver enzyme competition. Ask your doctor about alternative statins (rosuvastatin and pravastatin have fewer CYP interactions) or spacing doses 12 hours apart. CoQ10 supplementation may help with statin-related muscle discomfort.
St. John's Wort makes Zocor much less effective at lowering cholesterol.
Take Simvastatin in the evening when hepatic cholesterol synthesis peaks (exception: atorvastatin and rosuvastatin have long half-lives and can be taken any time). St. Johns Wort can be taken at a separate meal. Avoid St. John's Wort (reduces statin levels via CYP3A4 induction) and grapefruit extract (increases levels). Report any unexplained muscle pain or weakness.
Monitor for any unusual symptoms and report them to your healthcare provider promptly.
Statin interactions often involve liver enzyme competition. Ask your doctor about alternative statins (rosuvastatin and pravastatin have fewer CYP interactions) or spacing doses 12 hours apart. CoQ10 supplementation may help with statin-related muscle discomfort.
Ask your doctor: "Is there a safer alternative to St. Johns Wort that I can take with Simvastatin?" Bring a list of ALL supplements and medications you take.
Or browse the full interaction database (121,000+ pairs).